The Ju-52
tri-motor
was first built in the 1930s, yet remained in service for more than a
quarter century. This transport made its maiden flight in April 1931 and
flew with Lufthansa Airlines. Three years later a heavy bomber version
appeared, but was obsolete by 1939, but because of its
durability, simplicity of design, and handling characteristics it
continued to serve throughout WW II as a versatile workhorse of the
German transport fleet. See: Ju-52
Military Version. Approximately 30 different countries have flown Ju 52s.